Alternating-current electromagnetic reciprocating motor



April 6, 1965 P. A. MAccHloNl ETAL 3,177,386

ALTERNATING-CURRENT ELECTROMAGNETIC RECIPROCATING MOTOR 3 Sheets--Shee1J l Filed Nov. 7, 1962 ATTORNEQS ALTERNATING-CURRENT ELECTROMAGNETIC RECIPROCATING MOTOR 3 Sheets-Sheet 2 Filed Nov. 7, 1962 INVENTORS April 6, 1965 ALTERNATING- P. A. MAccHroNl ETAL 3,177,386 CURRENT ELECTROMAGNETIC RECIPROCATING MOTOR Filed Nov. '7, 1962 3 Sheets-Sheet 3 VI L* INVENTORS ATTORNEYS United States Patent C) 3,177,386 ALTERNATMQG-CUNT ELECTRMAGNE'HC v RECIPROCA'HNG MGTR Pietro Aurelio Macchioui and Luigi Macchioni, beth of 8 Corso S. Martino, Turin, italy Filed Nov. 7, 1962, Ser. No. 236,101 Claims priority, application Italy, Nov. 14, 1961, 20,560/ 61 3 Claims. (Cl. S10-30) This invention relates to improvements in electro magnetic hammers operating on alternating current either direct or through a rectifier, of the type in which the striker is secured to the movable portion of the laminated bundle the stationary part of which comprises three branches, namely an intermediate one extending through the coil and two lateral ones embracing the coil from diametrically opposed side, and wherein the striker is movably mounted in the direction of the coil axis between two pre-stressed springs. The one of the two springs is more powerful and maintains the striker constantly in a position such that the movable armature is removed from the stationary armature of the electromagnet, whereas the other spring or so-called synchronizer spring is adapted to insure the necessary synchronism of the striker movement and variation in magnetic ow acting in the stationary and movable armatures of the electromagnet.

it is an object of this invention to provide improvements concerning both the manner of guiding and supporting the striker and the tool end which is supported on the hammer casing and is acted upon by the striker.

According to this invention these objects are attained by supporting and guiding the striker during its reciprocating movement, at least at its end which is secured to the movable armature of the electromagnet, by a discshaped diaphragm, which is preferably made of a synthetic material resisting fatigue and temperatures arising in operation of the hammer, secured to the periphery of the striker and retained in an annular groove cut in the portion of the hammer casing which surrounds the striker.

According to a further feature ofthe improved hammer the synchronizer spring encloses an annular lug of synthetic material similar to the material of which the diaphragm is made, which isadapted to absorb shocks due to excessively long strokes of the striker in the direction oi the end of the cooperating tool.

According to a further characteristic feature of the improved hammer the tool end carried by the hammer casing is guided in a bushing mounted in the corresponding casing portion, said bushing being made likewise of synthetic material or of metal and being formed in the latter case with radial holes connecting its inner face with an annular chamber iilled with lubricant, tightly sealed and bored in the portion of the hammer casing which surrounds and supports the tool end acted upon by the striker.

Further characteristic features and advanatges of this invention will be clearly understood from the appended description referring by way of a non-limiting example to the accompanying drawings which show embodiments of the improved electromagnetic hammer, and wherein:

FIGURE 1 is a longitudinal sectional View of an embodiment of the improved hammer,

FIGURE 2 is a sectional view on line lI-Ii of FIG- URE l,

FIGURE 3 is a side elevational View partly in section of a further embodiment of the hammer,

FGURE 4 is a view of the hammer in the direction of the arrow IV indicated in FIGURE 3,

FIGURE 5 is a longitudinal elevational view of a further hammer embodiment,

ice

FIGURE 6 is a sectional view thereof on line VI-VI of FIGURE 5,

FlGURE 7 is a sectional view on line VII-V11 of FlGURE 6,

FIGURE 8 is a view o1 the same hammer in the direction of the arrow V111 in FIGURE 6.

Corresponding hammer parts are denoted by the same reference numerals through the figures.

FEGURES l to 4 show embodiments of an electromagnetic hamrner of a light weight type, in which the coil 1 fed through a cable 2 through the interposition of a switch 3 operated from a push-button 4, is surrounded lateral branches 5 of the stationary armature in the form of a laminated bundle of known construction, and is fitted on an intermediate branch 6 of the stationary armature. This armature is fitted into the outer casing i which is subdivided along the longitudinal middle plane oi the hammer and joined by screws 3 acting at the same time to secure the armature to the casing '7. The portion of the casing surrounding the coil is provided with a plurality of holes 7 allowing air ventilation and cooling of the coii.

The movable ararnture is likewise in the form of a laminated bundle of T shape, having an intermediate branch 9 reaching within the coil and formed with side expansions it?. The intermediate branch engages through a dovetail-shaped joint 11 the striker 12 to which it is moreover welded at 13. A tubular member 14 is iitted on the striker 12 and holds by means of an annular step 15 the inner edge of a diaphragm 16 made of resilient synthetic material resisting fatigue and temperatures up to C. The outer edge of the membrane 16 is held between an annular step 17 on the casing 7 and an edge itl of an annular member 19 which is in turn held in position by the end of the cylindrical conical casing Ztl surrounding the striker. The bore of the annular member 19 is appreciably larger than the bore of the tubular member lditted on the striker, and has a surface extending radially to the coil axis, acting as an abutment for the spring 2l which is pre-stressed and the other end of which bears on a collar 22 on the tubular member 14. The collar 22 is formed with a seating adapted to receive one end of the synchronizer spring 23 which bears at its other end on an annular member 24 acting to hold the outer edge of a further annular disc-shaped diaphragm 25 against a step 26 formed on the casing 20. The inner edge of the diaphragm 25 is clamped through the interposition or suitable washers by screwing a screw threaded collar Z7 on the end or" the striker 12 cooperating with a tool U. The synchronizer spring 23 houses a ring 28 likewise made of synthetic material like the one employed for the diaphragms 16 and 25, adapted to absorb shocks which might arise on excessively long strokes oi the striker 12 in the direction of the tool.

The end of the casing Ztl has screwed thereon a cap 23 within which a spool-shaped member of synthetic material 29 is arranged. The bore in the spool receives with a tight t the tapered end 30 cooperating with the striker on the tool U.

The intermediate gap 31 left between the intermediate branches 6 and 9 of the stationary and movable armature is rectilinear and perpendicular to the coil axis and should therefore be considered as being of conventional construction. However, the gaps separating the ends of the side branches 5 from the side expansions lil on the movable armature are of special shape and are formed at their ends with short sections perpendicular to the coil axis, joined to longer sections inclined through a small angle to the said axis. This configuration causes the spacing of the inclined sections of the side portions of the stati-onary and movable armatures to amount in the maxia mum stroke position (5 to 6 mm.) of the striker in the direction of the tool, lonly to a few tenths of a millimeter, thereby practically annulling any resistance against flow of the magnetic flux between the two armature portions and almost fully avoiding any dispersion of ux.

The movement performed by the diaphragrns lid and 25 during operation of the hammer set up within the hammer casing Ventilating streams which efliciently cool the movable parts of the hammer, more particularly the coil. In order to enhance these streams the hammer casing hassuitable holes bored therethrough.

The embodiment shown in FIGURE 3 does not differ from the embodiment according to FIGURES l and 2 as far as the magnetic part is concerned, and merely differs in respect of the manner of guiding and supporting the striker and lthe. tool end reaching within the hammer casing. According to this construction a chamber 32 is formed in the front portion of the casing 20 also acting as a cap and is internally defined by a bushing 33 through which radial holes 34 are bored. T-he chamber 32 is lled with grease or thick oil and is tightly sealed on one side by a ange 35 holding in position a seal 36 of synthetic material which also aets to clean the end 3@ of the tool U inserted within the bore in the bushing 33. The latter moreover receives an end 12a of the striker which is thereby lubricated through the ow of oil Vor grease through the holes 34 similarly to the tool end 3th The tubular member I4 is provided with a collar 37 adapted to bear against the edge 38 of the annular member I9 in order to prevent objectionable shocks during Vthe attraction stroke of the stationary and movable armatures.

The embodiment shown in FIGURES 5 to 8 relates to a heavier type hammer and is similar in constructional principles to the hammer shown in FIGURE 3. Similarly to the hammer shown in FIGURE 3 the tubular member 12 is shorter than the one of FIGURE 1 and the facing ends of the opposing and synchronizer springs, respectively, bear on a ring 39 screwed to the middle striker portion.

i Materials apt to withstand fatigue and temperatures arising in operation of the hammer are for instance the materials known by the trade names Vulkolan manufactured and distributed by the German firm of Bayer and Gaco manufactured and distributed by the rm of Angus, Wallyend, England, respectively.

What we claim is:

1. Alternating-current electromagnetic hammer having a casing and in said casing a coil, a movable and a stationary armature adjacent said coil, a striker secured to said movable armature `and `movable therewith in the direction of the coil axis, two prestressed springs namely a reaction spring and a synchronizer spring each interposed Y between said casing and said striker and holding the latter in such a position as to maintain the movable armature spaced from the stationary armature, and at least one disc-shaped resilient diaphragm made of synthetic material resistant to fatigue and high temperature, interposed between said casing and said striker for supporting the latter and for guiding its reciprocating movement.

2. Alternating-current electromagnetic hammer as set forth in claim l comprising furthermore a ring of synthetic material similar to the diaphragm material, said ring being located within said synchronizer spring, an annular abutment member coaxial with and adjacent to said ring, said ring adapted to contact said abutment member in order to absorb shocks due to casual excessively long strokes of the striker under the action of the reaction spring.

3. The alternating-current electromagnetic hammer of claim l, wherein the portion of said hammer casing surrounding said coil is provided with a plurality of substantially radially extending bores, so that air Ventilating and cooling said coil can be exchanged through said bores due to the movement of said diaphragm anchored to said striker.

No references cited.

. MILTON O. HIRSHFIELD, Primary Examiner. 

1. ALTERNATING-CURRENT ELECTROMAGNETIC HAMMER HAVING A CASING AND IN SAID CASING A COIL, A MOVABLE AND A STATIONARY ARMATURE ADJACENT SAID COIL, A STRIKER SECURED TO SAID MOVABLE ARMATURE AND MOVABLE THEREWITH IN THE DIRECTION OF THE COIL AXIS, TWO PRESTRESSED SPRINGS NAMELY A REACTION SPRING AND A SYNCHRONIZER SPRING EACH INTERPOSED BETWEEN SAID CASING AND SAID STRIKER AND HOLDING THE LATTER IN SUCH A POSITION AS TO MAINTAIN THE MOVABLE ARMATURE SPACED FROM THE STATIONARY ARMATURE, AND AT LEAST ONE DISC-SHAPED RESILIENT DIAPHRAGM MADE OF SYNTHETIC MA- 